Primary oscillatory instability in a rotating disk–cylinder system with aspect (height/radius) ratio varying from 0.1 to 1

Gelfgat, Alexander

doi:10.1088/0169-5983/47/3/035502

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…For very thin cavities (γ≈0.1), Gelfgat (2015) has observed that the flow becomes unstable for Reynolds numbers Re∼O(10 4 ) and with large azimuthal wave numbers m. These spiral patterns with around 20 arms and their different transitions have been the subject of many experimental studies in the 90s (see for instance Schouveiler et al 1998, Schouveiler et al 2001and Gauthier et al 2002, or the review by Launder et al 2010. They find their origin in the crossflow instability of the Bödewadt layer on the stator and were recently simulated by Lopez et al (2009).…”

Section: Thin Cylindrical Rotor/stator Cavitiesmentioning

confidence: 98%

Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number

Lachize¹,

Verhille²,

Gal³

2016

Fluid Dyn. Res.

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This paper reports an experimental investigation of a turbulent flow confined within a rotor/stator cavity of aspect ratio close to unity at high Reynolds number. The experiments have been driven by changing both the rotation rate of the disk and the thermodynamical properties of the working fluid. This fluid is sulfur hexafluoride (SF 6 ) whose physical properties are adjusted by imposing the operating temperature and the absolute pressure in the pressurized vessel, especially near the critical point of SF 6 reached for T c = 45.58 • C, P c = 37.55 bar. This original setup allows to obtain Reynolds numbers as high as 2 10 7 together with compressibility effects as the Mach number can reach 0.5. Pressure measurements reveal that the resulting fully turbulent flow shows both a direct and an inverse cascade as observed in rotating turbulence and in accordance with Kraichnan conjecture for 2D-turbulence. The spectra are however dominated by low-frequency peaks, which are subharmonics of the rotating disk frequency, involving large scale structures at small azimuthal wavenumbers. These modes appear for a Reynolds number around 10 5 and experience a transition at a critical Reynolds number Re c ≈ 10 6 . Moreover they show an unexpected non linear behavior that we understand with the help of a low dimensional amplitude equations.

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Section: Thin Cylindrical Rotor/stator Cavitiesmentioning

confidence: 98%

Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number

Lachize¹,

Verhille²,

Gal³

2016

Fluid Dyn. Res.

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Integral transform solution of swirling laminar flows in cylindrical cavities with rotating end walls

Cruz

Pereira

Macêdo

et al. 2021

J Braz. Soc. Mech. Sci. Eng.

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Large scale motions of multiple limit-cycle high Reynolds number annular and toroidal rotor/stator cavities

2017

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Rotating cavity flows are essential components of industrial applications but their dynamics are still not fully understood when it comes to the relation between the fluid organization and monitored pressure fluctuations. From computer hard-drives to turbo-pumps of space launchers, designed devices often produce flow oscillations that can either destroy the component prematurely or produce too much noise. In such a context, large scale dynamics of high Reynolds number rotor/stator cavities need better understanding especially at the flow limit-cycle or associated statistically stationary state. In particular, the influence of curvature as well as cavity aspect ratio on the large scale organization and flow stability at a fixed rotating disc Reynolds number is fundamental. To probe such flows, wall-resolved large eddy simulation is applied to two different rotor/stator cylindrical cavities and one annular cavity. Validation of the predictions proves the method to be suited and to capture the disc boundary layer patterns reported in the literature. It is then shown that in complement to these disc boundary layer analyses, at the limit-cycle the rotating flows exhibit characteristic patterns at mid-height in the homogeneous core pointing the importance of large scale features. Indeed, dynamic modal decomposition reveals that the entire flow dynamics are driven by only a handful of atomic modes whose combination links the oscillatory patterns observed in the boundary layers as well as in the core of the cavity. These fluctuations form macro-structures, born in the unstable stator boundary layer and extending through the homogeneous inviscid core to the rotating disc boundary layer, causing its instability under some conditions. More importantly, the macro-structures significantly differ depending on the configuration pointing the need for deeper understanding of the influence of geometrical parameters as well as operating conditions.

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Primary oscillatory instability in a rotating disk–cylinder system with aspect (height/radius) ratio varying from 0.1 to 1

Cited by 4 publications

References 32 publications

Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number

Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number

Integral transform solution of swirling laminar flows in cylindrical cavities with rotating end walls

Large scale motions of multiple limit-cycle high Reynolds number annular and toroidal rotor/stator cavities

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